Processes and systems for making inorganic fibers

ABSTRACT

Inorganic fiber production processes and systems are disclosed. One process includes providing a molten inorganic fiberizable material, forming substantially vertical primary fibers from the molten material, and attenuating the primary fibers using an oxy-fuel fiberization burner. Other processes include forming a composition comprising combustion gases, aspirated air and inorganic fibers, and preheating a fuel stream and/or an oxidant stream prior to combustion in a fiberization burner using heat developed during the process. Flame temperature of fiberization burners may be controlled by monitoring various burner parameters. This abstract allows a searcher or other reader to quickly ascertain the subject matter of the disclosure. It will not be used to interpret or limit the scope or meaning of the claims.

BACKGROUND OF THE INVENTION

1. Field of Invention

The present invention relates generally to the field of inorganic fiberproduction and systems, and more specifically to heat exchange andcontrol strategies useful in flame attenuation fiberization processesproducing inorganic microfibers and other fibers.

2. Related Art

One process for manufacturing fine diameter mineral fibers, e.g.discrete length, glass fibers typically ranging from about 0.2 micronsto about 7.0 microns in diameter, is the flame attenuation process. Inthis process, an electrically or gas flame heated pot or meltercontaining a molten fiberizable material such as glass batch materialsor preformed marbles are melted and drawn from a plurality of outletorifices of a bushing to form continuous primary filaments. The primarycontinuous filaments are drawn from the heated pot or melter by pullrolls which also function to feed the continuous primary filaments intoa high temperature, high energy, gas flame that further attenuates thecontinuous primary filaments and forms short length, fine diameterfibers from the continuous primary filaments. These attenuating burnershave extremely high gas flow rates in order to stretch the filamentswhile they are heated so as to reduce their diameter. As the attenuatedfilaments cool below the melting temperature of the glass, thesefilaments are broken by the force of the attenuating blast into fiberswithin a predetermined range of lengths, this range being a function ofthe operational parameters and the configuration of the attenuationzone. A filament guide with a plurality of grooves therein, guides andsupports the continuous primary filaments into the flame so that thecontinuous primary filaments can be introduced into the flame at aspecific location without being blown haphazardly about by the flame.The discrete length, fine diameter fibers, thus formed, are generallycollected to form a fibrous blanket with the fibers randomly orientedwithin the blanket.

Energy costs continue to increase, spurring efforts to find ways toreduce the amount of fuel in mineral fiber manufacturing. The highvelocity attenuation blast entrains cooler air from its surroundings.This low energy, low velocity air is mixed with the attenuation streamthereby diluting it and reducing both its temperature and velocity. Thecapability of the attenuating apparatus to reduce fiber diameter (i.e.,to improve the filtration or insulating capabilities of the material) ishampered by this unrestricted stream dilution. To offset thedisadvantages of dilution, more gas must be burned to produce highertemperatures. Fiberization process operators have resorted torestricting dilution by providing a shroud around the attenuation regionwhich limits the entrainment of dilution air by restricting the accessof the surroundings to the region. The shroud also confines the heatthereby increasing the temperature in the attenuation zone. Severalopenings are provided in the shroud to permit a restricted amount ofdilution air to be beneficially entrained by the attenuation stream. Thedilution air from at least one of the openings may be provided with apreheater which uses waste heat rising from the attenuating burner toheat the air. The position of the stream of gases can also be adjustedwithin the shroud by adjusting the amount of air inspirated above andbelow the centerline of the blast or stream. The inspirated air streammay be directed to create turbulence in the combined stream, causing theprimary filaments to adopt a serpentine path within the attenuation zonewhich increases the length of time each primary is exposed to the heatof the attenuation zone and thereby improves fiber attenuation (i.e.,reduces fiber diameter).

Despite these advances in the art, there is still a need for furtherenergy efficiency in mineral fiberization processes. Because of thetremendous amounts energy required in glass tank furnaces, steel blastfurnaces, and rotary furnaces, combined with regulations limiting theamount of NOx and SOx emissions, operators in those industries have usedoxygen-enriched air to decrease energy usage and emissions. These tendto be very high temperature processes (at least, 820° C., 1500° F.). Invery high temperature processes in large furnaces, NO_(x) formation ispromoted by long residence times of oxygen and nitrogen molecules in hotregions of the flame and the furnace. The use of substantially pureoxygen (about 90% O₂ or higher) instead of air as the oxidant has provento be very successful in reducing the NO_(x) emissions by as much as90%, since all nitrogen is eliminated. However; substitution of air bysubstantially pure oxygen increases the flame temperature, and thuscreates regions in the larger furnaces where the reactivity of nitrogenwith oxygen is high, and wherein the formation of NO_(x) mayproportionally increase, even though it is globally decreased whencompared to combustion with air. Use has been made of regenerative andrecuperative furnaces in the aforementioned industries to recover someof the heat in the high temperature effluent gases. Regenerative glasstank furnaces use hot combustion gases that otherwise would be vented tothe atmosphere to heat an intermediate heat transfer material, such asceramic balls held in towers. Typically two towers are used, so that onetower is heated by combustion gases while the other tower has airflowing there through to preheat the combustion air before enteringburners. The towers are switched in cyclic fashion. Recuperative glasstank furnaces preheat combustion air using heat exchange between coolair and combustion gases. In addition to air preheating, commercialgrade oxygen and oxygen-enriched air may be preheated employing director indirect heat exchange (through one or more heat exchange fluids,such as an inert gas) using specially designed heat exchangers. However,none of these techniques, despite their being available for sometime,have ever been used in mineral fiberization processes and systems. Thismay be due to any of a variety of factors. Not only are the fields ofuse quite different, but the nature of the molten material and equipmentbeing different (fibers vs. large pools of molten material, usage ofburners to attenuate fibers vs. usage of burners for melting) leads tovery different problems to be solved, despite the fact that decreasedenergy usage is a common goal of many industries, including both thefloat glass and mineral fiber industries. As the end use of mineralfibers depends on the physical properties of the fibers, such as theirability to be dispersed in liquids and slurries, or their ability tofunction as filter media or insulation, producers are careful not tochange a process that produces acceptable fibers for a small decrease inenergy consumption.

Because of this it would be an advance in the fiberization art to reduceenergy requirements a significant amount in mineral fiberizationprocesses to make their implementation attractive, particularly insituations where the fiber physical properties are acceptable, or evenbetter than acceptable, in terms of higher quality fibers and productsemploying the fibers, such as filtration and insulation products.

SUMMARY OF THE INVENTION

In accordance with the present invention, processes and systems aredescribed that unexpectedly produce better quality fibers thanpreviously known fiberization processes and systems. By controllingburner flame temperature and/or other burner operating parameters ofoxy-fuel fiberization burners, processes and systems of the inventionallow production of inorganic fibers having greater average strength andlength while reducing or eliminating shot compared to conventionalair-fuel fiberization burners that do not use an oxygen-enrichedoxidant. In certain embodiments, for example when oxygen is notavailable, or available but too expensive, processes and systems aredescribed employing preheating air and/or fuel with auxiliary heatsources such as electrical resistance elements, coal-fired high pressuresteam, and the like. One goal of processes and systems of the inventionis to elevate the combustion gas temperature, or flame temperature,leaving the burner. Energy economics may dictate using thesealternatives in lieu of oxygen. When an oxygen-enriched oxidant isemployed, heat recovery techniques may also be used as the oxy-fuelflame temperatures are higher than air-fuel flame temperatures.

A first aspect of the invention are processes of making fibers, oneprocess comprising:

-   -   (a) providing a molten inorganic fiberizable material;    -   (b) forming one or more substantially vertical primary fibers        from the molten material; and    -   (c) attenuating the primary fibers using a flame of an oxy-fuel        burner.

If oxygen or an oxygen-enriched oxidant is not available, the air and/orfuel entering the burner may be preheated using heat recovery techniques(capturing some of the heat otherwise wasted in the process) or throughuse of auxiliary heating means, thereby increasing flame temperature.Processes of the invention include those wherein the oxy-fuel burnerproduces a jet of hot combustion gases or flame to attenuate the primaryfibers. The combustion gases combine with aspirated air and inattenuated fibers to form a composition, and substantially all of theattenuated inorganic fibers are separated from the composition to forman effluent gas stream comprising the combustion gases and aspiratedexcess air. Processes of the invention include those wherein either thefuel and/or one or more oxidants is preheated by exchanging heat with atleast a portion of the effluent gas stream. Other processes of theinvention are those wherein the preheating comprises exchanging heatwith at least a portion of the composition comprising combustion gases,aspirated air and inorganic fibers, as would be present in a fibercollection chamber, which may be a cylindrical or other shaped chutedownstream of the burner and where aspirated or entrained air is used tocool the fibers. Process of the invention include those wherein aprimary oxidant (for example air) and fuel are premixed prior to beingcombusted in the burner, and a secondary oxidant enriched with oxygen isalso used in the oxy-fuel burner. Other processes of the inventioninclude those wherein the primary oxidant and the fuel are mixed in situin the burner. The primary oxidant may be selected from air,oxygen-enriched air, and industrial grade oxygen. Processes of theinvention include those wherein a secondary oxidant is injected into theburner, wherein the secondary oxidant may be any grade of oxygen, suchas industrial grade oxygen produced cryogenically, by adsorptionprocesses, or membrane processes. The primary oxidant may be compressedprior to combusting with the fuel in the burner. For example, theprimary oxidant may be air and the preheating may comprise exchangingheat with at least a portion of the composition prior to compressing theair. A secondary oxidant may be injected into the primary oxidant beforeor after compressing the primary oxidant. Alternatively, the primaryoxidant may be air and the preheating may comprise exchanging heat withat least a portion of the effluent gas stream prior to compressing theair. Other processes of the invention are those wherein a secondaryoxidant may be injected into the primary oxidant before or aftercompressing the primary oxidant. Yet other processes of the inventionare those wherein a secondary oxidant is combined with the primaryoxidant to form a tertiary oxidant prior to combustion of the fuel inthe burner. The tertiary oxidant may be preheated, as well as theoptionally the fuel, prior to combustion of the fuel with tertiaryoxidant. Yet another alternative process of the invention is lancing asecondary oxidant into the combustion gases emanating from the burner,prior to the combustion gases aspirating air in the collection chamber.

All process embodiments of the invention may be controlled by one ormore controllers. For example, fiberization burner flame temperature maybe controlled by monitoring one or more parameters selected fromvelocity of the fuel, velocity of one or more oxidants, mass flow rateof the fuel, mass flow rate of one or more oxidants, energy content ofthe fuel, temperature of the fuel as it enters the burner, temperatureof the oxidant as it enters the burner, temperature of the effluent,pressure of the oxidant entering the burner, humidity of the oxidant,burner geometry, combustion ratio, and combinations thereof. Otherprocesses of the invention may employ a heat transfer fluid, such as aninorganic, substantially inert gas, such as nitrogen, argon, helium,non-combustible mixtures of hydrogen and helium, and the like. The heattransfer fluid may first pick up heat from the effluent gas stream orthe composition comprising combustion gases, inspirated air, and fibers,and give up its heat in one or more heat exchangers to one or more ofthe fuel, primary oxidant, secondary oxidant, or tertiary oxidant.

Another aspect of the invention are systems, one system comprising:

-   -   (a) an assembly comprising a molten inorganic fiberizable        material container, and a bushing for forming substantially        vertical primary fibers from the molten material; and    -   (b) an oxy-fuel burner for attenuating the primary fibers.

Certain systems of the invention may include heat recovery or auxiliaryheating means for preheating air and/or fuel if an oxygen-enrichedoxidant is not available. Systems of the invention include thosecomprising a compressor for compressing a primary oxidant, systemscomprising means for injecting a secondary oxidant enriched in oxygeninto the burner or into the primary oxidant, typically a pipe ordouble-barreled pipe having coolant in the annulus between pipes. Othersystems of the invention include those wherein a heat exchanger isemployed, which may be a gas to gas heat exchanger adapted to exchangeheat between an effluent stream and streams selected from the fuel, theprimary oxidant, the secondary oxidant, and a mixture of primary andsecondary oxidants. Certain systems of the invention include a gas togas heat exchanger adapted to exchange heat between an effluent streamand streams selected from the fuel, the primary oxidant, and both thefuel and primary oxidant. Exemplary systems of the invention comprise acombustion controller which receives on or more input parametersselected from velocity of the fuel, velocity of one or more oxidants,mass flow rate of the fuel, mass flow rate of one or more oxidants,energy content of the fuel, temperature of the fuel as it enters theburner, temperatures of the oxidants as they enter the burner, pressuresof the oxidants entering the burner, humidity of the oxidants, burnergeometry, oxidation ratio, temperature of the effluent and combinationsthereof, and employs a control algorithm to control combustiontemperature based on one or more of these input parameters.

Processes and systems of the invention will become more apparent uponreview of the brief description of the drawings, the detaileddescription of the invention, and the claims that follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The manner in which the objectives of the invention and other desirablecharacteristics can be obtained is explained in the followingdescription and attached drawings in which:

FIG. 1 is a schematic process flow diagram of a prior art fiberizationprocess that may benefit from the improvements presented by the presentinvention;

FIGS. 2-5 are schematic block diagrammatical views of four non-limitingsystems and processes in accordance with the invention;

FIG. 6 is a perspective view of a prior art fiberization burner;

FIG. 7 is a perspective view of the fiberization burner of FIG. 6modified to include non-cooled secondary oxidant injection;

FIG. 8 is a cross-sectional view of the burner of FIG. 7 along 8-8;

FIG. 9 is a perspective view of the fiberization burner of FIG. 6modified to include a gas-cooled injector that may be used to injectsecondary oxidant or, with modification, fuel;

FIG. 10 is a cross-sectional view of the gas-cooled injector of FIG. 9along 10-10;

FIG. 11 is a perspective view of the fiberization burner of FIG. 6modified to include a liquid-cooled injector that may be used to injectsecondary oxidant or, with modification, fuel;

FIG. 12 is a cross-sectional view of the gas-cooled injector of FIG. 11along 12-12;

FIG. 13 is a plan view of a nozzle mix fuel/oxidant burner useful in theinvention;

FIG. 14 is an end elevation view of the burner of FIG. 13 and FIG. 15 aschematic illustrating some dimensions of the burner of FIG. 13; and

FIG. 16 is a schematic block diagram of a combustion process controlscheme in accordance with the invention.

It is to be noted, however, that the appended drawings are not to scaleand illustrate only typical embodiments of this invention, and aretherefore not to be considered limiting of its scope, for the inventionmay admit to other equally effective embodiments.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments may be possible.

All phrases, derivations, collocations and multiword expressions usedherein, in particular in the claims that follow, are expressly notlimited to nouns and verbs. It is apparent that meanings are not justexpressed by nouns and verbs or single words. Languages use a variety ofways to express content. The existence of inventive concepts and theways in which these are expressed varies in language-cultures. Forexample, many lexicalized compounds in Germanic languages are oftenexpressed as adjective-noun combinations, noun-preposition-nouncombinations or derivations in Romanic languages. The possibility toinclude phrases, derivations and collocations in the claims is essentialfor high-quality patents, making it possible to reduce expressions totheir conceptual content, and all possible conceptual combinations ofwords that are compatible with such content (either within a language oracross languages) are intended to be included in the used phrases.

The invention describes inorganic material fiberization processes andsystems. Although the invention is not limited to so-called “microfiber”production processes and systems, it is helpful to define the term as astarting point. As used herein, “microfibers” are defined as fibershaving a mean diameter ranging from about 0.05 to about 3.5 micrometers,more typically from about 0.1 to about 1.0 micrometers. Microfibersproduced by processes and systems of the invention may have a length todiameter ratio of at least about 5:1 and more usually from about 3000:1to about 10:1. The length to diameter ratio of the microfibers mostoften averages from about 10:1 to about 2000:1. The average length anddiameter of the microfibers can be controlled by controlling thecombustion process, and secondarily by the composition and flow rate ofthe molten inorganic material being fiberized. Generally, microfibersproduced using processes and systems of the invention have an averagelength of less than about 0.05 inches. Normally, the microfibers have anaverage length ranging from about 1 to about 500 micrometers, moreusually ranging from about 10 to about 300 micrometers, and most oftenthe fiber length averages from about 25 to about 50 micrometers.Procedures for determining the average diameters and lengths ofparticular batches of microfibers are well known to those skilled in theart and need not be repeated.

“Fiberization” is used as a verb unless otherwise noted, and meansforming short fibers, which may or may not be microfibers, from aprimary, relatively continuous fiber using a hot blast process modifiedin accordance with the invention, where hot combustion gases attenuatethe primary fiber, and aspirated air is used to cool the attenuatedfibers and cause the attenuated primary fibers to break into short,staple fibers.

Given that safety, decreased energy consumption, production capacity,and fiber physical properties are primary concerns, and that there isconsiderable investment in existing equipment, it would be an advance inthe art if existing fiberization systems and processes could be modifiedto increase safety, energy efficiency, productivity, and productquality, or new systems designed for these purposes whose capital outlaywould be returned quickly through energy efficiency and increased salesof product. This invention offers processes and systems for thesepurposes.

Referring now to the figures, FIG. 1 is a schematic process flow diagramof a prior art air-fuel fiberization process that may benefit from thesystems and methods of the invention. Glass marbles are transported to adistribution hopper 102 and then into a heated pot 104, which then meltsthe marbles into molten glass. Marbles may be transported to feed hopper102 with a distribution manifold to a plurality of heated pots 104, thefeed rate to heated pots 104 being a function of pot temperature androller 110 rpm. Heated pot 104, sometimes referred to the marble pot,may typically comprise a metallic cylinder heated with a heating jacketusing premixed natural gas burners on its side walls. The bottom ofmarble pot 104 may be formed from a metal alloy comprising multipleholes ranging from about 0.05 inch to 0.5 inch in diameter, depending onthe glass fiber product being made, through which the molten glass isdrawn into primary fibers 106 (only one primary fiber is shown). Primaryfiber 106 may be pulled and directed by rollers 112 and 114 and by fiberguides 113 and 114 through a heat containment shield 108. Shield 108 mayextend in space between the bottom of marble pot 104 to the top of thefirst set of rollers 110, and functions to control the cooling rate ofthe primary fiber. The objective is to keep the primary fiber as hot aspossible without damaging roller pad material in the rollers. Inaddition to the heat shield, heat sources, such as infrared sources maybe placed in the spaces before rollers 110 and 112 or after the rollers.

A fiberization burner 116 functions to produce a hot flame at acontrolled temperature, velocity, and oxidation state in the systems andmethods of the invention. The glass fiber product to be manufactured isa function of the mass flow rate of the glass, the primary glass fiberdiameter, the flame temperature produced by burner 116, the slot sizeand pressure inside of burner 116, and the product code fiber diameter.Benefits of using oxygen or oxygen-enriched air as an oxidant infiberization burners include the higher flame temperature fiberization,which leads to increased fiber tensile strength, longer fibers, andreduce production or elimination of shot, or looser process control toavoid producing shot. Fluctuations in humidity are reduced, andvariation in fiber quality is reduced.

In both the prior art process depicted in FIG. 1 and the systems andprocesses of the invention, a collection chamber 118 comprising agenerally cylindrical chute collects short fibers and entrains air intochamber 118 to rapidly cool the molten fibers. The fiber are then routedto a larger section of chamber 118 where at the far end a fiber pickupdrum 120 collects the fibers, where a secondary fiber pickup apparatus122, such as vacuum ducting or a roller, removes the fibers. Pickup drum120 is typically a rotating perforated steel cylinder with a filtermaterial suitable for collecting fibers secured to the outer surface ofthe cylinder, with aide of negative pressure on the inside of drum 120.Combustion gases, any particulates, and excess air (in the prior artprocess, and in addition excess oxygen in systems and methods of theinvention) pass through drum 120 through ducting 124 and flow through aparticulate removal device 126, with aide of an exhaust fan 128. A heatexchanger 130 may be used to cool exhaust gases, which exit toatmosphere at 136. In prior art system and methods using air-fuelcombustion, cool air 132 is used to cool the exhaust, resulting inwarmed air 134 of low grade heat content, largely unusable in heatrecovery. However, with the higher temperatures experienced in oxy-fuelcombustion of the invention, this heat may be recovered and used invarious ways, as further explained herein.

In light of the higher fiberization burner flame temperatures involvedwhen using oxy-fuel fiberization burners (from about 2200 to about 3200°F. as opposed to 1900° F. for air-fuel fiberization flame temperatures),opportunities exist also for heat recovery and energy savings. FIGS. 2-5are schematic block diagrammatical views of four non-limiting systemsand processes in accordance with the invention. FIG. 2 illustrates asystem and process embodiment 100 where a hot effluent stream may beused to preheat fuel, primary oxidant (for example, air), and/orsecondary oxidant (for example oxygen or oxygen-enriched air).Embodiment 100 includes one or more fiberization burners 2, a collectionunit 4, a fiber separation unit 6, and a heat exchanger 8. Fiberizationburner 2 burns a fuel F which may arrive at burner 2 through conduit 10,12, and/or 14, using a primary oxidant PO which may arrive throughconduit 16 and/or 18, and may receive a secondary oxidant SO throughconduit 20 and/or 22. Combustion gases leave burner 2 as indicated by aconduit 24, but the invention is not so limited, as there may not besignificant space between burner 2 and collection unit 4. Air 26 isinspirated into collection unit 4 to cool attenuated fibers coming fromburner 2. Air 26 may be ambient air or non-ambient air, such as chilledor heated air. A composition comprising combustion gases, inspiratedair, and fibers leaves collection unit 4, as indicated by a conduit 28,to fiber separation unit 6. Once again, although the composition isillustrated traversing to fiber separation unit 6 through a conduit 28,the invention is not so limited, and this is for illustration purposesonly to indicate the general direction of movement of compositionsthrough the system. Fiber separation unit separates stream 28 into afiber stream 30 and a hot effluent stream 32 using known means. Hoteffluent stream 32 transfers some of its heat to one or more of thefuel, primary oxidant, and secondary oxidant streams in heat exchanger8, and then exits as a cooled effluent stream 34. In certain embodimentsof the invention, hot effluent stream 32 maybe separated into multiplestreams entering heat exchanger 8. Similarly, cool effluent stream 34may be a composite of multiple cool effluent streams exiting heatexchanger 8. The details depend on the specific heat transfer load anddesign of heat exchanger 8, as chosen by the engineer. Suitable valving,some of which is indicated in FIG. 2, may be employed to direct all,some, or none of a particular stream through heat exchanger 8. If morethan two of fuel, primary oxidant, and secondary oxidant are to gainheat from the hot effluent stream, heat exchanger design will bedictated to be either separate units, or one unit having suitablecompartments, gaskets, and the like, to prevent premature mixing ofoxidant and fuel, or of primary oxidant and secondary oxidant, asdesired. Other units maybe added to this system and process withdiverging from the invention, such as a particulate recovery unit instream 32. Furthermore, the flow of solid material is not illustrated,and the system would include fiber precursor holding tanks, such as feedhoppers, marble pots, heat containment equipment, primary fiber guidesand rollers, and the like, the descriptions of which are fairly wellknown to those of ordinary skill in the inorganic fiberization art as torequire no further explanation.

FIG. 3 illustrates an embodiment 200 wherein heat from the compositioncomprising fibers, combustion gases, and inspirated air is employed topreheat fuel, primary oxidant, and/or secondary oxidant. The samereference numerals are used in the various embodiments to refer toidentical components. Embodiment 200 also includes one or morefiberization burners 2, a collection unit 4, and a fiber separation unit6, however in embodiment 200, the heat exchanger 8 of embodiment 100 ofFIG. 2 is replaced with one or more heats exchangers 9A and 9B,illustrated in FIG. 3 as comprising shells of heat exchangers. Fuel Fmay be routed through conduit 36 to heat exchanger 9A, and return aspreheated fuel in conduit 38, and then be routed to burner 2. Similarly,or alternatively, primary oxidant may be routed through a conduit 40 toheat exchanger 9A and return as preheated primary oxidant in a conduit42 and be routed into burner 2, and a secondary oxidant may be routedthrough a conduit 44 to heat exchanger 9B and return as preheatedsecondary oxidant in a conduit 46 and be routed to burner 2.

In certain other embodiments of the invention, not illustrated in thefigures, combinations of embodiments 100 and 200 of FIGS. 2 and 3,respectively, may be employed. For example, primary oxidant could bepreheated by heat exchange with hot effluent gases as depicted generallyin FIG. 2, while fuel could be preheated by heat exchange with theequipment illustrated in FIG. 3. All of these various systems andprocesses and their equivalents are consider within the presentinvention.

FIGS. 4 and 5 illustrate two non-limiting embodiments wherein anintermediate heat transfer fluid may be used to accept heat from a hotstream, and then transfer some of that heat to a fuel and/or oxidantstream. FIG. 4 illustrates an embodiment 300 that is somewhat similar toembodiment 100 of FIG. 2, however, a hot effluent stream 33 passesthrough a heat exchanger 50 to transfer some of its heat to a cool heattransfer fluid entering heat exchanger 50, for example via a conduit 13.A warm heat transfer fluid leaves heat exchanger 50, for example via aconduit 11, which continues on to another heat exchanger 52 to exchangeheat with fuel entering through conduit 54, primary oxidant throughconduit 58, and/or secondary oxidant 62. For clarity, various valves arenot shown, but those of skill in the art will realize that some, all, ornone of each stream (fuel, primary oxidant, and secondary oxidant) needbe preheated in any given operation. Non-preheated fuel, primaryoxidant, and secondary oxidant may be routed directly to burner 2through conduits 56, 60, and 64, for example. Furthermore, heatexchangers 50 and 52 may be a single unit, or multiple units, and may bearranged in series or parallel as desired for any particular case.Conduits may be added or deleted in accordance with the particularembodiment in question, heat transfer load, production quotas, and thelike. Safety relief vales are not illustrated, but would be included inmany of the streams, for example in conduit 13 transporting heated heattransfer fluid.

FIG. 5 illustrates an embodiment 400 that is somewhat similar toembodiment 200 of FIG. 2, however, a warm heat transfer fluid stream 15,having picked up heat from combustion gases, inspirated air and fibersin heat exchangers 9A and 9B, is routed through a heat exchanger 53 topreheat a cool fuel stream 66, a cool primary oxidant stream 70, and/ora cool secondary oxidant stream 74. A cooled heat transfer fluid leavesheat exchanger 53 via a conduit 17 and returns to heat exchangers 9A and9B to complete the cycle. Once again, for clarity, various valves arenot shown, but those of skill in the art will realize that some, all, ornone of each stream (fuel, primary oxidant, and secondary oxidant) needbe preheated in any given operation. Non-preheat fuel, primary oxidant,and secondary oxidant may be routed directly to burner 2 throughconduits 68, 72, and 76, for example. Furthermore, heat exchangers 53,9A and 9B may be single units, or multiple units, and may be arranged inseries or parallel as desired for any particular case. Safety reliefvales are not illustrated, but would be included in many of the streams,for example in conduit 17 transporting heated heat transfer fluid.

The heat transfer fluid used may be any gaseous, liquid, or somecombination of gaseous and liquid composition that functions or iscapable of being modified to function as a heat transfer fluid. Gaseousheat transfer fluids may be selected from inert inorganic gases, such asnitrogen, argon, and helium, inert organic gases such as fluoro-,chloro- and chlorofluorocarbons, including perfluorinated versions, suchas tetrafluoromethane, and hexafluoroethane, and tetrafluoroethylene,and the like, and mixtures of inert gases with small portions ofnon-inert gases, such as hydrogen, and inert liquids which may beorganic, inorganic, or some combination thereof, for example, saltsolutions, glycol solutions, and the like. Other possible heat transferfluids include steam, carbon dioxide, or mixtures thereof with nitrogen.

Any combination of processes and systems of FIGS. 4 and 5 may beenvisioned, and indeed any combination of processes and systems of FIGS.2-5, as may be desired. More heat transfer equipment will entailincreased capital expenditure, which, however will be offset bydecreased energy usage. Detailed but routine calculations may beperformed to determine the most cost effective process and system.

FIG. 16 is a schematic block diagram of one non-limiting combustionprocess control scheme in accordance with the invention. A mastercontroller 78 is shown, but the invention is not so limited, as anycombination of controllers could be used. The controller may be selectedfrom PI controllers, PID controllers (including any known or reasonablyforeseeable variations of these), and computes a residual equal to adifference between a measured value and a set point to produce an outputto one or more control elements. The controller may compute the residualcontinuously or non-continuously. Other possible implementations of theinvention are those wherein the controller comprises more specializedcontrol strategies, such as strategies selected from feed forward,cascade control, internal feedback loops, model predictive control,neural networks, and Kalman filtering techniques. In FIG. 16, the linesand boxes numbered 80-87 may represent sensors, for example sensors forthe following parameters, which are merely exemplary examples:

-   -   80=V_(fuel), velocity of fuel entering burner;    -   81=V_(PO), velocity of primary oxidant entering burner;    -   82=V_(SO), velocity of secondary oxidant entering burner;    -   83=M_(fuel), mass flow rate of fuel entering burner;    -   84=M_(PO), mass flow rate of primary oxidant entering burner;    -   85=T_(fuel), temperature of fuel entering burner;    -   87=T_(PO), temperature of primary oxidant entering burner;    -   88=P_(PO), pressure of primary oxidant entering burner;    -   89=H_(PO); humidity of primary oxidant.

The lines and boxes numbered 88-95 may represent control signals andactuators, respectively, for outputs for the following parameters, whichare merely exemplary:

-   -   88=V_(fuel), velocity of fuel entering burner;    -   89=V_(PO), velocity of primary oxidant entering burner;    -   90=M_(fuel), mass flow rate of fuel entering burner;    -   91=M_(SO), mass flow rate of secondary oxidant entering burner;    -   92=T_(fuel), temperature of fuel entering burner;    -   93=T_(PO), temperature of primary oxidant entering burner;    -   94=P_(SO), pressure of secondary oxidant entering burner;    -   95=M_(EFF) (or M_(HTF)), mass flow rate of hot effluent (or heat        transfer fluid).

Other parameters may be included as inputs, such as desired fiberdiameter and/or length 96, burner geometry 97, and combustion ratio 98.

The term “control”, used as a transitive verb, means to verify orregulate by comparing with a standard or desired value. Control may beclosed loop, feedback, feed-forward, cascade, model predictive,adaptive, heuristic and combinations thereof. The term “controller”means a device at least capable of accepting input from sensors andmeters in real time or near-real time, and sending commands directly toburner control elements, and/or to local devices associated with burnercontrol elements able to accept commands. A controller may also becapable of accepting input from human operators; accessing databases,such as relational databases; sending data to and accessing data indatabases, data warehouses or data marts; and sending information to andaccepting input from a display device readable by a human. A controllermay also interface with or have integrated therewith one or moresoftware application modules, and may supervise interaction betweendatabases and one or more software application modules.

The phrase “PID controller” means a controller using proportional,integral, and derivative features. In some cases the derivative mode maynot be used or its influence reduced significantly so that thecontroller may be deemed a PI controller. It will also be recognized bythose of skill in the control art that there are existing variations ofPI and PID controllers, depending on how the discretization isperformed. These known and foreseeable variations of PI, PID and othercontrollers are considered within the invention.

Controllers useful in the systems and methods of the invention may varyin their details. One PID controller useful in the invention may beexpressed mathematically as in Equation 1:u(t)=Kp[e(t)+1/Ti·∫e(t)dt+Td·è(t)]  (1)

-   -   wherein:    -   ∫ means integrate;    -   è(t) means the time derivative;    -   u(t) is controller output, which may be burner flame        temperature, for example;    -   e(t) means difference between a desired and measured (real time)        value;    -   Td is a constant for describing the derivative part of the        algorithm (the derivative part may be filtered to avoid deriving        high frequencies);    -   Ti is a constant for describing the integrating part of the        algorithm; and    -   Kp is a proportional gain constant.

In the s-plane (Laplace), the PID controller may be expressed as(Equation 2):Hr(s)=Kp[1+1/Tis+Tds/(1+Tfs)]  (2)

-   -   wherein:    -   s is the variable in the s-plane; and    -   Tf is a constant describing the filtering part of the derivative        part of the algorithm.

For discretization, a variety of transforms may be employed, and someconstants may or may not be useful. For example, the T_(f) constant maynot be necessary in some instances, but may be especially useful inother scenarios. As one discretization example, the z-transform may beused, meaning that the integral part of the algorithm may beapproximated by using a trapezoid model of the form (Equation 3):s=(1−z−1)/T  (3)

while the derivative part may be approximated using an Euler model(Equation 4):s=2/T−(1−z−1)/(1+z−1)  (4)

-   -   wherein T is the sampling time.

The resulting discrete model may then be used directly in the combustionor burner control algorithm. Other discrete models, derived using othertransforms, are useful in the invention, and will be apparent to controltechnicians or control engineers of ordinary skill.

The controller may utilize Model Predictive Control (MPC). MPC is anadvanced multivariable control method for use in multiple input/multipleoutput (MIMO) systems. An overview of industrial Model PredictiveControl can be found at: www.che.utexas.edu/˜qin/cpcv/cpcv14.html. MPCcomputes a sequence of manipulated variable adjustments in order tooptimise the future behavior of the process in question. At each controltime k, MPC solves a dynamic optimization problem using a model of thecontrolled system, so as to optimize future behavior (at time k+1, k+2 .. . k+n) over a prediction horizon n. This is again performed at timek+1, k+2 . . . MPC may use any derived objective function, such asQuadratic Performance Objective, and the like, including weightingfunctions of manipulated variables and measurements. Dynamics of theprocess and/or system to be controlled are described in an explicitmodel of the process and/or system, which may be obtained for example bymathematical modeling, or estimated from test data of the real processand/or system. Some techniques to determine some of the dynamics of thesystem and/or process to be controlled include step response models,impulse response models, and other linear or non-linear models. Often anaccurate model is not necessary. Input and output constraints may beincluded in the problem formulation so that future constraint violationsare anticipated and prevented, such as hard constraints, softconstraints, set point constraints, funnel constraints, return oncapital constraints, and the like. It may be difficult to explicitlystate stability of an MPC control scheme, and in certain embodiments ofthe present invention it may be necessary to use nonlinear MPC. Inso-called advanced control of various systems, PID control may be usedon strong mono-variable loops with few or nonproblematic interactions,while one or more networks of MPC might be used, or other multivariablecontrol structures, for strong interconnected loops. Furthermore,computing time considerations may be a limiting factor. Some embodimentsmay employ nonlinear MPC.

The feed forward algorithm, if used, will in the most general sense betask specific, meaning that it will be specially designed to the task itis designed to solve. This specific design might be difficult to design,but a lot is gained by using a more general algorithm, such as a firstor second order filter with a given gain and time constants.

FIG. 6 is a perspective view of a prior art fiberization burner 150,having a stainless steel or other metallic shell 152, a refractoryburner block 154 defining a burner slot 156 and a combustion chamber158. An air-fuel mix manifold, 160 and 162 routes air and fuel,typically natural gas, to the combustion chamber 158. Manifold 160 and162 is mounted to burner block 154 through mounting holes 164 (fourtypically) through flange 166.

FIG. 7 is a perspective view, and FIG. 8 is a cross-sectional viewthrough section 8-8, of the fiberization burner of FIG. 6 modified toinclude non-cooled secondary oxidant injection in accordance with oneburner useful in the present invention. Burner 170 includes twosecondary oxidant manifolds 172 and 174, which may be stainless steelpipe or other alloy pipe, each having a series of holes therein foraccepting a corresponding number of ceramic tubes 176 through secondaryoxidant is charged into combustion chamber 158.

In operation of fiberization burners useful in the invention, thininorganic primary fibers are directed by means of guides and rollersinto the flame produced by the fiberization burner. The mass flow rateof the inorganic material, for example glass, is a function of theprimary fiber diameter, the flame temperature of the burner, the burnergeometry, for example slot size of the burner, the pressure in theburner, and the product code fiber diameter. The process operatingconditions are generally not independent values but have some degree ofinteraction. Oxygen-enhanced oxidant/fuel fiberization is markedlydifferent than the traditional air-fuel fiberization process. Thegeneral principle is to operate combustion in the burner in a mannerthat replaces some of the air with a separate source of oxygen. Theoverall combustion ratio may not change. The process of combining fueland oxygen-enriched oxidant will occur in the burner combustion chamberafter the gases have passed over the flame arrestor safety device. Theflame temperature of the combustion gases can be controlled by varyingthe air to oxygen ratio in of the oxidant. In accordance with thesystems and processes of the invention, a standard burner firing 1600scfh of natural gas, from 0 to about 400 scfh of oxygen may be safelyinjected into the burner in conjunction with an appropriate air flow.

FIG. 9 is a perspective view of the fiberization burner of FIG. 6modified to include a gas-cooled injector that may be used to injectsecondary oxidant or, with modification, fuel. FIG. 10 is across-sectional view of an injector 1000 useful in burner 900, takenalong section 10-10 of FIG. 9. Burner 900 includes the metallic shell152, refractory burner block 154, and 156, and air-fuel mix manifold 160and 162 of prior art burner embodiment 150 of FIG. 6, and in additionincludes an injector 1000 comprising a metallic rectangular outer tube180 and a similar but smaller rectangular tube 184 positioned inside ofouter rectangular tube 180, as illustrated in FIG. 10. Inner rectangulartube 180 and inner rectangular tube 184 define a volume through which acooling gas may enter through inlets 188 and 189, and exit throughoutlets 190 and 191. Fuel or secondary oxidant may be injected throughmanifolds 181 and 182, which may be stainless steel or other alloy metaltubes. A plurality of holes 186 may be positioned uniformly near thebottom of tube 181 and top of tube 182 to inject fuel or secondaryoxidant. Since tubes 181 and 182 are exposed to hot combustion gases,cooling is provided. Bolts or other fasteners 192 may be used to fasteninjector 1200 in burner 1100. More or mess than two gas coolant inletsand outlets may be provided in other embodiments as desired, and thesealternative embodiments are considered within the invention.

FIG. 11 is a perspective view of the fiberization burner of FIG. 6modified to include a liquid-cooled injector that may be used to injectsecondary oxidant or, with modification, fuel. FIG. 12 a cross-sectionalview of a liquid-cooled injector 1200 used in burner 1110, taken alongsection 12-12 of FIG. 11. Burner 1100 and injector 1200 are similar toburner 900 and gas-cooled injector 1000 of FIGS. 9 and 10, except thatfor liquid ingress and egress only one inlet and one outlet need beprovided. Embodiments employing more than one liquid coolant inlet andmore than one liquid coolant outlet are considered within the invention,but may not be necessary in all circumstances due to better cooling ofthe liquid.

FIG. 13 is a plan view of a nozzle mix fuel/oxidant burner 1300 usefulin the invention, and FIG. 14 is an end elevation view of the burner ofFIG. 13. In burner 1300, oxygen-enriched oxidant and fuel are directedto flow through separate pluralities of tubes 206 and 207, respectively,ending in separate nozzles 214. An oxygen-enriched oxidant inlet 202supplies a chamber or manifold 204 which then feed tubes 206. Similarly,fuel inlet 210 supplies a fuel chamber or manifold 212, which directsfuel through tubes 207. Fuel is then combusted at nozzles 214. Thecombustion product gases are directed through a chute defined by arefractory spacer 208, and then at the inorganic primary fibers forfiberization. The number of tubes oxidant 206 and fuel tubes 207 mayvary widely, but generally the number of oxidant tubes ranges from about50 to about 150, while the number of fuel tubes 207 may range from about25 to about 75. The length of the tubes, L_(OX) and L_(f), may eachrange from about, 3 to about 10 inches, while the diameter may rangefrom about 1/32 inch up to 0.5 inch. The spacing between tubes may beuniform and equal to about one tube diameter; alternatively the tubesmay be arranged side-by-side. The fuel and oxidant inlets may bestainless steel or other alloy pipes. As may be seen in FIG. 15, thisparticular burner configuration provides a similar effect as a premixslot type burner in producing a wide, flat flame for fiberization. Thewidth W of slot 156 may range from about 3 to about 36 inches, and theheight of slot H may range from about 0.05 inch to about 1 inch. Depth Dmay range form about 0.5 to about 5 inches, depending on the supportstrength required.

Fiberization burners and injectors are an important aspect of theinventive processes and systems, and are claimed in applicant'sco-pending patent application Ser. No. ______, filed concurrentlyherewith.

According to the present invention, the fuel and the oxidant areintroduced in the burner either through separate tubes in the burnerassembly, or are premixed. The term “fuel”, according to this invention,means a combustible composition comprising a major portion of, forexample, methane, natural gas, liquefied natural gas, propane, atomizedoil or the like (either in gaseous or liquid form). Fuels useful in theinvention may comprise minor amounts of non-fuels therein, includingoxidants, for purposes such as premixing the fuel with the oxidant, oratomizing liquid fuels. The term “oxidant”, according to the presentinvention, means a gas with an oxygen molar concentration of at least50%. Such oxidants include oxygen-enriched air containing at least 50%vol., oxygen such as “industrially” pure oxygen (99.5%) produced by acryogenic air separation plant or non-pure oxygen produced by e.g. avacuum swing adsorption process or membrane permeation (about 90% vol.O₂ or more).

The total quantities of fuel and oxidant used by the combustion systemare such that the flow of oxygen may range from about 0.9 to about 1.2of the theoretical stoichiometric flow of oxygen necessary to obtain thecomplete combustion of the fuel flow. Another expression of thisstatement is that the combustion ratio is between 0.9 and 1.2.

The velocity of the fuel gas in the various burners depends on theburner geometry used, but generally is at least about 15 m/s. The upperlimit of fuel velocity depends primarily on the desired attenuated fibergeometry and the geometry of the burner; if the fuel velocity is toolow, the flame temperature may be too low, providing in adequatefiberization, which is not desired, and if the fuel flow is too high,flame might impinge on downstream equipment, or be wasted, which is alsonot desired.

Additionally, the invention also provides stabilization of the flamewith an auxiliary injection of fuel and/or oxidant gases. Injection ofthe oxidant fluid may be made by premix of fuel and primary oxidant,usually air, and in addition secondary oxidant injection, using either anon-cooled injector, a gas-cooled injector, or a liquid—cooled injector,as explained in reference to the figures. When injecting secondaryoxidant such as industrial oxygen in a gas-cooled or liquid-cooledburner, the hole diameter 186 (FIG. 10) or tube 176 diameter in anon-cooled injector (FIG. 8) maybe such that the secondary oxidantvelocity does not exceed about 200 ft/sec at 400 scfh flow rate. Theinternal pressure of the burner should not exceed about 10 psig.

Systems and processes of the present invention are intended to be used,for example, to replace air-fuel combustion systems in already existingfiberization burners, and/or to be used as the main source of energy innew burners.

Suitable materials for the refractory block in the burners are fusedzirconia (ZrO₂), fused cast AZS (alumina-zirconia-silica), rebonded AZS,or fused cast alumina (Al₂O₃). The choice of a particular material isdictated among other parameters by the chemistry and type of inorganicfibers to be produced.

In embodiments of the invention employing a heat transfer fluid, it ispossible for the hot intermediate fluid to transfer heat to the oxidantor the fuel either indirectly by transferring heat through the walls ofa heat exchanger, or a portion of the hot intermediate fluid couldexchange heat directly by mixing with the oxidant or the fuel. In mostcases, the heat transfer will be more economical and safer if the heattransfer is indirect, in other words by use of a heat exchanger wherethe intermediate fluid does not mix with the oxidant or the fuel, but itis important to note that both means of exchanging heat are contemplatedby the present invention. Further, the intermediate fluid could beheated by the hot flue gases by either of the two mechanisms justmentioned.

In certain embodiments, the primary means for transferring heatcomprises one or more heat exchangers selected from the group consistingof ceramic heat exchangers, known in the industry as ceramicrecuperators, and metallic heat exchangers further referred to asmetallic recuperators. Systems in accordance with the invention includethose wherein the primary means for transferring heat are double shellradiation recuperators. Preheater means useful in the invention compriseheat exchangers selected from ceramic heat exchangers, metallic heatexchangers, regenerative means alternatively heated by the flow of hotintermediate fluid and cooled by the flow of oxidant or fuel that isheated thereby, and combinations thereof. In the case of regenerativemeans alternately heated by the flow of hot intermediate fluid andcooled by the flow of oxidant or fuel, there may be present two vesselscontaining an inert media, such as ceramic balls or pebbles. One vesselis used in a regeneration mode, wherein the ceramic balls, pebbles orother inert media are heated by hot intermediate fluid, while the otheris used during an operational mode to contact the fuel or oxidant inorder to transfer heat from the hot media to the fuel or oxidant, as thecase might be. The flow to the vessels is then switched at anappropriate time.

In certain systems and processes in accordance with the invention, thehot intermediate fluid exchanges heat with the fuel and oxidant inparallel preheater means, in other words, hot intermediate fluid issplit into two streams, one stream exchanging heat with the fuel in afirst burner preheater means, the second stream exchanging heat with theoxidant in a second burner preheater means. Alternatively, for safetyreasons, the intermediate fluid exchanges heat first with the oxidant inone or more oxidant preheaters, and then with the fuel in one or morefuel preheaters in series exchangers.

In other exemplary embodiments, the fuel path, oxidant path, and the hotintermediate fluid path may be defined by bores through a burner blockas is known in the burner art.

When the intermediate fluid is air, and the oxidant for combustion isoxygen, the hot air can be advantageously used as the combustion oxidantby directing the hot air flow to the burners, when the oxygen supply isinterrupted.

It must be understood from the description herein that the inventivesystems and processes are not strictly limited to embodiments whereinthe fuel and oxidant are heat exchanged with an intermediate fluid atthe same temperature of the intermediate fluid. In some embodiments, itis preferred to contact the hot intermediate fluid first with theoxidant, creating an intermediate fluid having a lower temperature, andsubsequently exchanging heat of this lower temperature intermediatefluid with the fuel. Also, as stated previously, in certain embodiments,it is contemplated that the hot intermediate fluid could be mixed withthe oxidant, the fuel or both.

Although only a few exemplary embodiments of this invention have beendescribed in detail above, those skilled in the art will readilyappreciate that many modifications are possible in the exemplaryembodiments without materially departing from the novel teachings andadvantages of this invention. Accordingly, all such modifications areintended to be included within the scope of this invention as defined inthe following claims. In the claims, no clauses are intended to be inthe means-plus-function format allowed by 35 U.S.C. § 112, paragraph 6unless “means for” is explicitly recited together with an associatedfunction. “Means for” clauses are intended to cover the structuresdescribed herein as performing the recited function and not onlystructural equivalents, but also equivalent structures.

1. A process comprising: (a) providing a molten inorganic fiberizablematerial; (b) forming one or more substantially vertical primary fibersfrom the molten material; and (c) attenuating the primary fibers using aflame of an oxy-fuel burner.
 2. The process of claim 1 comprisingforming a composition comprising combustion gases, aspirated air andinorganic fibers, and separating substantially all of the inorganicfibers from the composition to form an effluent gas stream.
 3. Theprocess of claim 2 comprising preheating a fuel and/or an oxidant streamby exchanging heat with at least a portion of the effluent gas stream.4. The process of claim 3 wherein the preheating comprises exchangingheat with at least a portion of the composition.
 5. The process of claim1 wherein a primary oxidant and fuel are premixed prior to beingcombusted in the burner.
 6. The process of claim 1 wherein a primaryoxidant and fuel are mixed in situ in the burner.
 7. The process ofclaim 5 or 6 wherein the primary oxidant is selected from air,oxygen-enriched air, and industrial grade oxygen.
 8. The process ofclaim 5 or 6 comprising injecting a secondary oxidant into the burner.9. The process of claim 8 wherein the secondary oxidant is industrialgrade oxygen.
 10. The process of claim 1 comprising compressing aprimary oxidant prior to combusting the fuel in the burner.
 11. Theprocess of claim 10 wherein the primary oxidant is air and the processcomprises preheating at least a portion of the air by exchanging heatwith at least a portion of a composition comprising combustion gases,aspirated air and inorganic fibers prior to compressing the air.
 12. Theprocess of claim 11 comprising injecting a secondary oxidant into theprimary oxidant after compressing the primary oxidant.
 13. The processof claim 2 comprising compressing a primary oxidant prior to combustingthe fuel in the burner.
 14. The process of claim 13 wherein the primaryoxidant is air and the process comprises preheating at least a portionof the air by exchanging heat with at least a portion of burnercombustion gases prior to compressing the air.
 15. The process of claim13 comprising injecting a secondary oxidant into the primary oxidantafter compressing the primary oxidant.
 16. The process of claim 1wherein a secondary oxidant is mixed with a primary oxidant to form atertiary oxidant prior to combustion of the fuel in the burner.
 17. Theprocess of claim 16 comprising preheating the tertiary oxidant andoptionally the fuel prior to combusting of the fuel with tertiaryoxidant.
 18. The process of claim 2 wherein a secondary oxidant ispreheated by heat exchange with at least a portion of the effluent gasstream.
 19. The process of claim 1 comprising lancing of the flameformed by the burner with a secondary oxidant.
 20. The process of claim1 comprising controlling burner flame temperature by monitoring one ormore parameters selected from velocity of the fuel, velocity of aprimary oxidant, mass flow rate of the fuel, mass flow rate of theprimary oxidant, energy content of the fuel, temperature of the fuel asit enters the burner, temperature of the primary oxidant as it entersthe burner, pressure of the primary oxidant entering the burner,humidity of the primary oxidant, burner geometry, oxidation ratio, andcombinations thereof.
 21. The process of claim 2 wherein the preheatingcomprises exchanging heat between at least a portion of a compositionand a heat transfer fluid to form a heated heat transfer fluid, andexchanging heat between the heated heat transfer fluid and the fueland/or a primary oxidant.
 22. The process of claim 2 wherein thepreheating comprises exchanging heat between at least a portion of theeffluent gas stream and a heat transfer fluid to form a heated heattransfer fluid, and exchanging heat between the heated heat transferfluid and the fuel and/or primary oxidant.
 23. A process comprising: (a)providing a molten inorganic fiberizable material; (b) forming one ormore substantially vertical primary fibers from the molten material; (c)attenuating the primary fibers using a flame of a burner; and (d)preheating an oxidant, a fuel, or both prior to entering the burner. 24.A process comprising: (a) providing an electrically or gas flame heatedpot or melter containing molten glass; (b) drawing continuous primaryfilaments of glass from a plurality of outlet orifices of a bushing, theprimary continuous filaments drawn from the heated pot or melter by pullrolls; (c) feeding the continuous primary filaments into a jet flame ofcombustion gases from an oxy-fuel burner combusting a fuel with anoxidant enriched with oxygen, the burner producing a flame having aflame temperature and energy sufficient to form attenuated primaryfilaments; (d) cooling the attenuated primary filaments below themelting temperature of the glass using aspirated air, resulting inbreaking the attenuated primary filaments to form fibers having apredetermined range of lengths and diameters; and (e) collecting thefibers while separating an effluent gas stream comprising combustiongases and aspirated air from the fibers.
 25. The process of claim 24wherein the oxidant is selected from oxygen-enriched air and industrialgrade oxygen.
 26. The process of claim 24 comprising wherein a secondaryoxidant enriched in oxygen is injected into the burner.
 27. The processof claim 24 comprising controlling combustion temperature by monitoringone or more parameters selected from flame temperature, velocity of thefuel, velocity of the oxidant, mass flow rate of the fuel, mass flowrate of the oxidant, energy content of the fuel, temperature of the fuelas it enters the burner, temperature of the oxidant as it enters theburner, pressure of the oxidant entering the burner, humidity of theoxidant, burner geometry, oxidation ratio, and combinations thereof. 28.The process of claim 24 wherein the burner operates at a pressureranging from about 10 to about 100 oz water column.
 29. A systemcomprising: (a) an assembly comprising a molten inorganic fiberizablematerial container, and a bushing for forming substantially verticalprimary fibers from the molten material; and (b) an oxy-fuel burneradapted to produce a flame and attenuate the substantially verticalprimary fibers.
 30. The system of claim 29 comprising a compressor forcompressing an oxidant.
 31. The system of claim 29 comprising means forinjecting a secondary oxidant enriched in oxygen into the burner or intoa primary oxidant.
 32. The system of claim 31 comprising a heatexchanger for preheating a fuel and/or the primary oxidant and/or thesecondary oxidant prior to combustion of the fuel in the burner usingheat developed during attenuating the fibers, wherein the heat exchangeris a gas to gas heat exchanger adapted to exchange heat between agaseous portion of the composition and streams selected from the fuel,the primary oxidant, the secondary oxidant, and a mixture of primary andsecondary oxidants.
 33. The system of claim 29 comprising a combustioncontroller which receives input parameters selected from flametemperature, velocity of the fuel, velocity of an oxidant, mass flowrate of the fuel, mass flow rate of an oxidant, energy content of thefuel, temperature of the fuel as it enters the burner, temperature of anoxidant as it enters the burner, pressure of an oxidant entering theburner, humidity of an oxidant, burner geometry, oxidation ratio, andcombinations thereof, and employs a control algorithm to control flametemperature based on one or more of these input parameters.
 34. A systemcomprising: (a) an assembly comprising a molten inorganic fiberizablematerial container, and a bushing for forming substantially verticalprimary fibers from the molten material; (b) a burner adapted to producea flame, the flame attenuating the substantially vertical primaryfibers; and (c) means for preheating an oxidant, a fuel, or both priorto entering the burner.
 35. The system of claim 34 comprising acombustion controller which receives input parameters selected fromflame temperature, velocity of fuel, velocity of oxidant, mass flow rateof the fuel, mass flow rate of an oxidant, energy content of the fuel,temperature of the fuel as it enters the burner, temperature of anoxidant as it enters the burner, pressure of an oxidant entering theburner, humidity of an oxidant, burner geometry, oxidation ratio, andcombinations thereof, and employs a control algorithm to control theflame temperature based on one or more of these input parameters.